1. Field of the Invention
The present invention generally relates to laser diode module (LD) and, more particularly to a package for enclosing an LD module.
2. Description of the Related Art
An LD module is used in optical telecommunications and includes an LD light source incorporating an LD chip, wherein the LD light source optically coupled to an optical fiber. The LD light source normally must be protected by a horsing and the LD chip is normally electrical connected to other electrical components such as a printed circuit board (PCB).
Referring to FIGS. 5 through 7B, are prior art. LD module includes a base 10, a laser diode 16, a photo diode 17, a housing 18 and a set of electrical terminals 11, 12, 13 and 14. The base 10 is made of a metal material, and has a cylindrical shape. Three through holes 103 are defined through the base 10. Three of the terminals 11, 12, 13 pass through the through holes 103. The terminals 11, 12, 13 are used to make electrical connections between the laser diode 16, the photo diode 17 and a PCB (not shown). One terminal 14 is soldered to the bottom of the base 10 and the PCB. A gap 15 is formed between each terminals 11, 12, 13 and the corresponding through hole 103, which is caulked with glass powder, and which becomes solid after baking at a high temperature.
The above described LD module has a very good seal between the baked glass power caulking and the terminals, but production of the module has some difficulties. First, glass powder is not easily positioned in the gaps without the help of special tools. Second, since the metal terminals and base are easily oxidized at high temperatures, the baking operation is generally done in a helium atmosphere below a pressure of 1xc3x9710xe2x88x928 Pascals. This environment is troublesome to achieve. Third, the melting point of the glass powder can be as high as 800 degrees, heating and cooling in a short time affects the stability of the solidifying glass powder. Therefore the process receivers a rather long time, generally from 8 to 10 hours, which causes problems of long production time and high cost.
Therefore, an object of the present invention is to provide a laser diode module having an improved structure to overcome the problems mentioned above.
An LD module in accordance with a preferred embodiment of the present invention, comprises a base, a laser diode, a photo diode, a housing and four contacts, wherein the contacts are fixed in the housing by plastic insert molding. The base is made of a metal material and has three through holes. A channel is defined on a bottom surface of the base and in communication with the through holes. Of the four contacts, one is soldered to the base and the others respectively pass through the three through holes and are plastic insert molded into the through holes such that they remain electrically isolated from the base. A dielectric package sealing material is used in the insert molding and fills the channel and through holes, isolating the contacts from the base.
Other objects, advantages and novel features of the present invention will be drawn from the following detailed description of a preferred embodiment of the present invention with attached drawings, in which: